Don't let the stalk of the broccoli go to waste! It has all the nutrients that the tops do. Peel the outer tough part of the stalk away and use the tender part to make this lovely soup.
Put the potatoes, onion, and carrots in a large pan and add vegetable broth. Add additional water if needed to just cover the vegetables.
Bring to the boil and reduce the heat and simmer for about 10 minutes.
Add the broccoli stalks, fennel and vegetable stock and continue to cook until all the vegetables are just tender.
Take off the heat and allow to cool a little before pouring into a blender and pureeing until smooth.
Taste, season and enjoy.